Edward r



(No Model.)

E. R. MARKHAM. SURPAGE GAGE.

Patented Sept. '30. 1890.

FIG. 2.

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WITNESSES:

93am Q By his A omeys, m. 6204 m C UNITED STATES PATENT OFFICE.

EDXVARD R. MARKHAM, OF OHIO OPEE FALLS, MASSACHUSETTS, ASSIGNOR TO THEJ. STEVENS ARMS AND TOOL COMPANY, OF SAME PLACE.

SURFACE-GAG E.

SPECIFICATION forming part of Letters Patent No. 37,308, dated September30, 1890.

Application filed April 7,1890- Serial No. 346,866. (No model.)

To all whom it may concern.-

Be it known that I, EDWARD R. MARKHAM, a citizen of the United States,residing in Ohicopee Falls, Hampden county, Massachusetts, have inventedcertain new and useful Improvements in Surface-Gages, of which thefollowing is a specification.

Surface-gages are ordinarily constructed with abase and an upright postprojecting therefrom, to which the pointer is fastened at any desiredheight-through the medium of a sliding clamping-sleeve. The adjustmentof the pointer is commonly effected by setting the sleeve at anyconvenient height and then turning the pointer on its swivel until itspoint is brought into contact with the surface to be tested, whereuponthe clamping-screw is tightened to fix the pointer in position. Tofacilitate the accurate adjustment of the pointer, surface gages havebeen made wherein the post is bodily adjustable up or down relatively tothe base by means of a screw at the base.

My invention is an improvement upon surface-gages of this class, itsobject being to improve the accuracy and stability of the instrument, tobring the adjusting-screw into more convenient position, and to enablethe screw to be constructed with graduations to be read to fractions ofan inch or other minute measurement after the manner of amicrometer-screw.

According to my invention the post is made tubular or as a sleeve and ismounted on a guiding-rod projecting up through it, which rod is fastenedfixedly to the base, the tubular sleeve being pressed upwardly by aspring against a screw or nut engaging the rod, and by turning which thesleeve is caused to move up or down. A pin and slot are provided toprevent the rotation of the sleeve.

Figure 1 of the accompanying drawings shows the preferred form of myimproved surface-gage in side elevation. Fig. 2 is a vertical transversesection thereof. Fig. 3 is a similar section of a slightly-modifiedconstruction. I

LetA designate the base; B, the upright post mounted thereon; O, thepointer, and D, the clamping-sleeve, by which the pointer is fastened tothe post. The pointer is mounted as usual by being passed through aclampingsocket in a divided swivel-head E, the shank e of whichconstitutes a screw-threaded rod passing through the ears cl of thedivided sleeve D with a thumb-nut F screwed on its protruding end, sothat by tightening this nut not only is the sleeve D contracted and madeto tightly embrace the post B, but the swivelhead E is clamped tightlyin position, so that it cannot turn or oscillate relatively to thesleeve D, and its two halves orj aws are pressed together so that theyembrace the pointer-rod tightly between them and prevent thelongitudinal movement of the pointer through the head. This is a usualmeans of attachment employed with surface-gages.

That which is characteristic of my invention is the construction of thepost B as a tubular sleeve adjustable up or down by sliding over aninternal guiding-rod H, which is fixed to the base A, and theconstruction of the adjusting-screw as a micrometer-screw, and itsarrangement at the top of the post. The ad justing-screw has a milledhead G, or other be adjusted with the greatest nicety and exactness tothe proper position.

The preferred construction is best shown in Fig. 2. The verticalguiding-rod H is fixed rigidly at its lower end to the base A, asclearly shown, and projects only partly through the tubular post orsleeve B. The adj usting-screw J enters the sleeve from above and itslower end screws into a threaded socket formed in the upper part of therod H. The shoulder j of the adjusting-screw, on which the head G 0 isformed, rests upon the upper end b of the sleeve and limits the upwardmovement thereof. The sleeve is kept pressed firmly upward against thisshoulder by a spring S, arranged in the annular space between thescrew-rod J and the sleeve, its lower end reacting against the top ofthe rod H and its upper end pressing upwardly against an inturned flangeor shoulder at the upper end of the sleeve, this shoulder beingpreferably formed in a thim- 10o ble (shown at b) screwed or otherwisefastened to the upper end of the sleeve to form the top or head of thetubular post. To prevent turning of the post it is formed at the lowerpart of the sleeve with a slot a, engaged by a pin 0, projecting fromthe rod II.

In order to facilitate the making of minute adjustments, the shoulder jis marked with micrometer-gradnations, which can be read with referenceto a mark f on the head I) of the sleeve. These graduations mayrepresent fractions of an inch or other minute measurement.

In the construction shown in Fig. 3 the guiding-rod II projects upentirely through and above the top of the tubular post or sleeve B, andthe adjustin -screw is in the form of a nut J, screwing on the threadedupper end of this red. The shoulder or neck of this nut may be graduatedafter the manner of micrometer screws, to the same effect as shown inFig. 1. The spring S is applied beneath the sleeve B, resting againstthe bottom of the recess in the base A, and pressing upwardly againstthe bot-tom end of the sleeve. Rotation of the latter is prevented byslots a and pins 0.

The vertically-adjustable sleeve and its internal guiding-rod H may bemounted and relatively arranged in numerous other ways and provided withother means for propelling the sleeve up or down. It is notessentialthat the sleeve be pressed by aspring against the adj Listing-screw,although this construc tion is preferable,because it takes up any lostmotion which might otherwise give rise to inaccuracy in the adjustment.Such lost motion might arise by looseness in the screwthreads in casethe adj usting-screw were employed without any spring to propel the postin both directions.

By my construction the adj Listing-screw is brought to the top of thepost instead of being at the base, as heretofore, which renders it muchmore convenient of access and enables its graduations to be readilyseen, so that to impart any given desired movement to the pointer thescrew can easily be turned to exactly the necessary extent by aid of thegrad nations. By my improved construction of the post so that it isguided interiorly by a rigid rod projecting up within it a considerabledistance, (or even entirely through it, if desired,) it has an extendedbearing-s11 rface for guiding it, so that it is more strongly andaccurately supported and guided than heretofore.

I claim as my invention the following defined novel features,substantially as hereinbefore specified, namely- 1. In a surfacegage,the combinatiomwith the base, of the upright post constructed to beadjustable vertically relatively to the base, aspring tending to move itin one direction, and a screw for adjusting it arranged to move it inthe other direction against the tension of said spring.

2. In a surfaeegage, the combination, with the base, of an uprighttubularpost or sleeve, a guiding-rod within said post and fixed to thebase,a spring arranged to press the tubular post upwardly and anadjusting-screw for forcing it downwardly.

In a surface-gage, the combinatiomwith the base, of an upright tubularpost or sleeve, a guiding-rod fixed to the base and projecting part waywithin the tubular post, and an adjusting-screw consisting of ascrew-rod entering the upper part of the post and screwing into saidguiding-rod and having a head above the post engaging the top thereof.

4. I11 a surface-gage, the combination, with the base, of an uprighttubular post or sleeve, a guiding-rod fixed to the base and projectingpart way within the tubular post, and an adj listing-screw consistin ofa screw-rod enterin g the upper part of the post and screwing into saidguiding-rod and having a head above the post bearing against the topthereof, and a spring arranged to press the tubular post upwardlyagainst the said head.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

EDXVARD R. MARKHAM.

\Vitnesses:

JAMES H. Looms, FRED W. SMITH.

